1. Field of the Invention
The preset invention relates to a robot controller for controlling a robot configured to supply and eject a workpiece processed by a machine tool, and relates to a processing system including the machine tool, the robot and the robot controller.
2. Description of the Related Art
When machine processing is carried out by using a machine tool, it is conventional to manage production control information relating to the machine tool by using an upper-level computer, in order to maintain processing quality. In detail, in a well-known method, the upper-level computer is connected to the machine tool via a network, actual production information, etc., is periodically transmitted from the machine tool to the upper-level computer, and the upper-level computer summarizes the transmitted information.
As relevant prior art documents, JP H11-123630 A discloses an NC device having an input means for an operator to input information; a display means capable of displaying a character and a figure; a communication means for transmitting and receiving information between a production control computer and the NC device; a display control means for displaying a notification information file which is a shared file in the production control computer on the display means; and a reply management means which writes reply information to the notification information, in a reply column arranged in the notification information file.
Further, JP 2006-039946 A discloses a production management system, wherein a signal is generated by sensing that processing of specific components have been completed by a plurality of machine tools configured to perform the same or the same kind of machining by using a sensor; the generated signal is input to a measurement controller; one set of measurement signal including a plurality of signals accumulated by the measurement controller is transmitted to a serial interface; the serial signal is transmitted to a network controller; and a personal computer, etc., accesses the network controller by an Ethernet (R) connection method so as to read production information in real-time.
Recently, a robot is often used to supply a workpiece to a machine tool before processing, and to eject the workpiece from the machine tool after processing. Further, the robot may be used to check processing accuracy of the processed workpiece, and may be used to exchange a work tool of the machine tool.
When supplying or ejecting a workpiece to or from a machine tool by using a robot, some production management information can be obtained only on the robot side. For example, when a supplying place and an ejecting place for the workpiece are detected by using a vision sensor attached to the robot, in order to obtain information as to how many unprocessed workpieces have been prepared on the supplying place and/or as to how many processed workpieces are located on the ejecting place, such information can basically be obtained by the robot only. When processing accuracy of a processed workpiece is inspected by the robot, only the robot can obtain information regarding the numbers of defective products and non-defective products. Further, when a work tool is exchanged by the robot, only the robot can obtain information as to which work tool processes each workpiece. Therefore, in some cases, only the robot, not the machine tool, has the production management information, which should be managed in order to maintain processing quality.
As described above, when the machine tool has some of the production management information and the robot has the remaining information, the upper-level computer must obtain the production management information from both the machine tool and the robot. In this regard, when the production management information of the machine tool and the robot are obtained at different times, there may be an inconsistency between the information from the machine tool and the information from the robot. For example, the total number of workpieces processed by the machine tool and the total number of workpieces supplied to the machine tool by the robot may not coincide with each other.
Generally, between the machine tool and the robot, a network is arranged for executing a program or transmitting an interlock signal, etc. In addition, it is necessary to connect another network to each of the machine tool and the robot, in order that the upper-level computer can obtain the production management information from the machine tool and the robot. In other words, it is necessary to arrange two types of networks, i.e., a network for connecting the machine tool and the robot to each other, and the other network for transmitting the production management information between the upper-level computer and the machine tool and between the upper-level computer and the robot.
In addition, in the machine tool, maintenance (removal of cutting chips, and exchange of the work tool, etc.) is often carried out, and electrical power to the machine tool is usually shut-off during maintenance. While the electrical power is shut-off, the production management information cannot be obtained from the machine tool.